Fiber forming torch



July 24, 1962 c. POTTER 3,045,278

FIBER FORMING TORCH Filed April 5, 1959 2 Sheets-Sheet 1 20 Fue. s

Prfe/my Zane 42 34 52 ATTORNEYS July 24, 1962 c. POTTER 3,045,278

FIBER FORMING TORCH Filed April 5, 1959 2 Sheets-Sheet 2 INVENTOR.CHARLES POTTER ATTORNEYS United States Patent Office 3,045,278 PatentedJuly 24, 1962 3,045,278 FIBER FORMING TORCH f l Charles Potter, SouthOrange, NJ., assigner to Engelhard Industries, Inc., Newark, NJ., acorporation of Delaware Filed Apr. 3, 1959, ser. Ne. 803,928 1p1 Claims.(Cl. 11s- 2.5)

This invention relates to combustion chambers or torches for formingtlber-s of materials such as quartz which have very high melting points.

'Fine quartz hbers are very diicult to make and are relatively-expensive with respect to many other fibers. This difficulty and highcost results principally from the high melting point of 17507 C. forquartz.

' Prior .techniques which have been proposed tor forming quartz fibershave employed commercial metallizing guns or torches and various otherarrangements. When these prior art `arrangements have been applied tothe formation of quartz fibers, however, it has been found that there isvery poor efliciency in the absorption of heat from the flame by thequartz, .and fthat the quartz fibers are formed at a very low rate, dueto Ithis poor utilization of heat.

Accordingly, increasing the production nate and reducing the cost ofmaking libers of high melting point materials iare the principal objectsof the present invention. Collateral objects of the invention includeincreasing the heat transfer etliciency and protecting the torch fromunnecessarily elevated temperatures. Stated in simpler terms, it isdesired to obtain more output per torch land more -output per unitvolume of input gas.

In addition, rods or laments of small diameter have normally been usedyas a starting point in prior art proca combustion chamber having aninlet end through Which -a rod of quartz or other high melting pointmaterial is fed. Quartz fibers and gases lare exhausted from the otherend. The end of the combustion chamber through which the quartz rod isfed is very nearly lair tight, and may therefore be termed the closedend of the chamber, in contrast to the opposite open or outlet endthrough which the quartz bers and other gases leave the combustionchamber. In the combustion chamber, suitable high temperature fuel andoxygen are applied peripherally and generally at right angles to theaxis of the rod, at a point spaced from the closed end of the combustionchamber. This direct application of heat to the quartz rod, generally at-right angles, permits high efficiency heat transfer to the quartz rodand raises the temperature of the rod to the melting point. Spacing thepoint of application of flame `to the rod from the closed end of thechamber permits suitable preheating of the rod. y

In addition, yaroundI the inner surface of .the outlet end of thecombustion chamber, air, steam or other gas under pressure is directedtoward the quartz rod .and outwardly from ther combustion chamber. Thisattenuates the molten quartz and draws iibers from it. It also has anaspirating or lsuction effect, and draws the flame and the combustionproducts centrally along the axis of the quartz rod to keep `the moltenquartz hot yas fibers are drawn olf. Furthermore, the -ame and the hotcombustion products are drawn out of the combustion chamber and awayfrom its walls .so that these walls `are not heated unduly. Formation ofbers depends upon having the 'nod of'high melting point material is fed,an open end,

arrangements for directing Ia flame generally perpendicular to the axiskof the rod, yand va peripheral outlet near the open end of lthe chamberfor providing a forceful annular gas jet directed toward the rod andoutward fnom the chamber.

In accordance with an additional feature of the invention, fthe llamemay be applied to the rod at alregion which is spaced from the closedend of the combustion chamber by a distance which is more than the innerradius of the chamber, to provide a preheating zone. Small 'bleed holesmay be provided .to supply lair under pressure to lthe preheat lzone ofthe combustion chamber to preclude the accumulation of silica vapor.

In accordance with a further feature of the invention, air, steam or-other gas under pressure may be supplied through `a jacket encompassingthe combustion chamber both rto the bleed holes in the preheat portionof the chamber and to the peripheral asprating outlet near the open endofthe combustion chamber. This arrangement serves to cool the inner wallof the combustion chamber and prevent overheating. `In addition, theheat transfer from the combustion Ichamber increases the temperature andenergy of the air stream thus increasing its velocity.

The aspiration effect provided by the peripheral outlet has theadvantage of permit-ting the combustion of larger gas volumes than wouldotherwise be possible. This increases the velocity of the gases formingthe exit jet and greatly increases the frictional shearing forces whichproduce the quartz fibers. The additional hea-t resulting from theeliicient use of the flame and large volume of combustion gas permitsthe use of quartz rods of relatively larger diameter in the process.These factors account to a considerable extent for the greatlyincreasedv 'FIGURE l is a cross sectional view of a combustion chamberor torch `for forming fibers of high melting point material inaccordance with the present invention;

FIGURE 2 is an alternative embodiment of the comlbuston chamber of'FIGURE 1 in which a cooling jacket is provided; Y

FIGURE 3 shows another modification of the invention in which fuel gasand oxygen are mixed within the combustion chamber itself; and FIGURE 4shows another fpost-mix arrangement for a combustion chamber. l Withreference to the drawings, FIGURE 1 shows an illustrative torch orcombusti-on chamber for formingl quartz rod 16 is fed into the closedend of the combustion chamber through the sealing element 18 whichprevents lbackfring through the closed end of the chamber.l

The torch of FIGURE l 3 Suitable rollers 20 and 22 may provide the drivefor feeding the rod 16 into the combustion chamber.

The quartz rod is heated by llame from the jets 24 through 31 which arespaced peripherally around the inner surface of the combustion chamber.Annular chambers 34 and 36`supp1y premixed fuel and oxygen to the jetopenings 24 through 31. The fuel is applied to the quartz rod 16 in adirection generally perpendicular to the axis of the rod. Morespecifically, as indicated by the arrows l38 and 40, for example, theflame from the jets is applied directly to the surface of the quartz rod16. This combustion directly on the surface of the rod is particularlyeffective for transferring heat to the rod. Accordingly, full heating ofthe quartz rod 16 is obtained up to the temperatures of about 2000" C.which are desirable for the forming of quartz fibers.

' In order to bring the quartz rod 16 up to the melting point, asuitable preheating zone 42 is provided within the combustion chamber.The preheating zone is provided both by the proper orientation of thejets 24 through 31 and lby the spacing of these jets at a significantdistance from the closed end of the combustion chamber. In this regard,it is noted that the jets are spaced from the closed end of thecombustion chamber .fby a distance which is greater than the minimuminner radius of the combustion chamber. While this distance is notoverly critical, a distance of this general order of magnitude, or asomewhat greater distance, is desirable in order to permit adequatepreheating of the rod in bringing it gradually up to the required highmelting temperature.

In regard to the orientation of the jets 24 through 31, it has beenmentioned that they should be oriented generally perpendicular to theaxis of the quartz rod 16. In this regard, slight deviations from exactperpendicularity within 45, or preferably within 30 of this angle, arewithin the contemplation of the present invention.

Toward the open end 14 of the combustion chamber, a blast of air orsteam is directed through the peripheral opening 44 toward the quartzrod and toward the open end of the combustion chamber. Air or steam tobe applied to the peripheral opening 44 is supplied from the tube 46 viathe annular opening 48. With regard to the connection of the tubes 46,50 and 51 to the torch assembly, conventional tube fittings may -beemployed. These ttings are not shown in detail in the present drawing.The Width of the peripheral opening 44 may be adjusted by rotating theannular member 54 at the open end 14 of the combustion chamber. As themember 54 is turned, its position with respect to the remainder of thecombustion chamber is shifted by means of the screw threads 52, and thewidth of the opening 44 is changed.

The quartz rod is preheated in the region designated 56; it is drawndown the region designated 58; and it is attenuated and blown intofibers in the region designated 60 in FIGURE l. It is again noted thatthe fibers are separated from the rod as the result of :frictionalshearing forces of the high velocity hot gases on the portion of thequartz Which `has been heated to the liquid phase.

The air blast through the peripheral opening 44 provides an aspiratngelect for the combustion chamber, and increases the velocity of thegases at the exit opening of the combustion chamber and particularly inthe region 60 as shown in FIGURE 1. In addition, the flames from thejets 25 and 31, for example, are deflected as indicated by the arrows 62and 64 toward the open end 14 of the combustion chamber. The ames arethus drawn along the molten portion 58 of the quartz rod and maintain itin the heated condition. Furthermore, the flame and the combustionproducts are directed away from the walls of the combustion chamber sothat it is not overheated. As can be readily imagined, this overheatingproblem is a serious one with temperatures of up to or slightly morethan 2000 C. being present ae the surface of the quartz 1'0 FIGURE 2 isan alternative embodiment of the arrangement of FIGURE l. The principal-additional feature of the arrangement of FIGURE 2 lies in the use of acooling jacket 72 which encompasses the major portion of the combustionchamber. The arrangement of FIGURE 2 also shows a premixing jacket 74 inwhich the oxygen and fuel gas are combined prior to application to thejet 76 and the other peripherally located jet openings. In order toavoid the accumulation of silica vapor in the preheat zone 78 of thefurnace, small air bleed holes 80 and 82 are provided, together withsuitable adjusting screws. Air flowing from the jacket 72 under pressurethrough these small bleed holes prevents the undesired accumulation ofsilica vapor in the preheating zone 78 of the furnace. The tubes 84 and86 pass through the cooling jacket 72 from the premix jacket 74 to thejet openings, without materially interfering with the flow of air fromthe closed end of the combustion chamber toward the peripheral opening88 at the open end of the combustion chamber. Suitable drill holes 90are provided for the passage of air from the cooling jacket 72 to theannular chamber 92 at the open end of the combustion chamber. It may benoted again that, in addition to the cooling effect and the convenientuse of bleed holes, the arrangement of FIGURE 2 provides for thetransfer of heat and the resultant increase in pressure of the gasapplied to the outlet 88. In other respects, the operation of the torchof FIGURE 2 is generally similar to that of FIGURE 1 as described above.

Two alternative forms of jet supply arrangements are disclosed inFIGURES 3 and 4. In FIGURE 3, fuel gas is supplied to the annularchamber 102, and oxygen is fed to the annular chamber 104. A series ofperipheral paired jets 111 through 114 are provided to mix the fuel gasand oxygen within the combustion chamber. This type of arrangement isdesignated a post-mix arrangement as contrasted with the premix flamejet employed in the arrangements of FIGURES l and 2.

A somewhat more elaborate post-mix arrangement is shown in FIGURE 4.Oxygen is supplied through tube 122 to the outer peripheral jacket 124.Fuel gas is coupled to the inner annular chamber 126 by the tube 128.Small tubes 130 are employed to carry the oxygen through the fuel gaschamber 126 to concentric jet openings such as those designated 132.This arrangement provides an improved mixing of the fuel gas Land oxygenwith somewhat less turbulence than that provided in the arrangement ofFIGURE 3. With regard to the open end of the combustion chambers ofFIGURES 3 and 4 and the other associated equipment which is not shown,these arrangements would correspond substantially with that of FIGURES 1and 2.

Any of a number of different types of fuel may be employed forcombination with oxygen. However, it is considered that acetylene,propane, methane or hydrogen are most suitable. The oxygen may besupplied under a pressure of from 15 to 90 pounds per square inch, forexample, and the fuel gas at any suitable pressure greater f than 15pounds per square inch. The air or steam for aspiratng and coolingpurposes may be at any desired pretslsure, preferably from .10 to poundsper square mc For simplicity of construction and to provide a preferredembodiment of the invention, the openings for the fuel have been shownas separate peripheral jets, and the opening for the aspiratng blast ofair or steam .has been disclosed as a continuous annular opening.However, the flame jets could be of a continuous annular form and theblast of air could be provided by a series of jets directed toward thequartz rod and the open end of the combustion chamber.

In the present discussion, the terms fused quartz and fused silica havebeen used loosely. In general, these terms and the additional termssilica glass and quartz glass are employed to refer to various types offused comme silica, and the different terms are employed to indicate thedegree of transparency of the material. However, the terms employed inthe present specification are intended to apply to quartz or silica inany of its known forms. Other details regarding terminology, the stateof fused quartz at various temperatures and so forth are set forth inthe National Bureau of Standards Circular 569 on Fused Quartz Fibers,issued January 25, 1956. In addition, the principles of the presentinvention are applicable to other high melting point materials such asthe,

ceramics and other similaror related materials having melting points ofthe same order of magnitude as that of fused quartz or silica.

The presen-t invention has been described inconjunction with a circulartorch or combustion chamber, and such an arrangement isto be preferred.It is recognized, however, that quartz rods of rectangular or squareshapes could also be processed by a torch or combustion chamber inaccordance with the principles of the present invention, and thecombustion chamber would then have a generally corresponding shape.

It is to be understood that the above described arrangements areillustrative of the application of the principles of the invention.Numerous other arrangements may be devised by those skilled in fthe artwithout departing from the spirit and scope of the invention.

What is claimed is:

l. In combination, a combustion chamber having a closed end and an openend, means for directing a rod of high melting point material throughthe closed end of said combustion chamber along an axis, toward the openend, means for directing llame generally perpendicularly to the axis,outlet means near the open end of the cham-ber for providing a forcefulperipheral gas jet di rected toward said axis and outwardly from thecombustion chamber, a -cooling jacket encompassing at least a portion ofsaid combustion chamber, means for coupling gas from said jacket to saidoutlet means, and means for supplying -gas under pressure to saidcooling jacket, whereby -the heat transferred from said combustionchamber to said gas increases the velocity of the gas jet from saidoutlet4 means.

2. In combination, a combustion chamber having a closed end and an openend, means for directing a rod of high melting point material throughthe closed end of said combustion chamber along 4an axis toward the openend, means for directing flame generally perpendicul-arly to theaxis,said flame directing means being spaced from the closed end of saidfurnace to provide -a preheating zone, outlet means near the open end ofthe chamber for providing a forceful peripheral gas jet directed towardsaid axis and outwardly from the combustion chamber, a cooling jacketencompassing at least a portion of saidv combustion chamber, includingsaid preheating zone, the wall between said cooling jacket and thepreheating zone o-f said combustion chamber being provided with at leastone small bleed hole lfor precluding the accumulation of silica vapor,means for coupling gas fro-m said j-acket to said outlet moana-and meansfor supplying gas under pressure to said cooling jacket.

3. In combina-tion, a combustion chamber having a closed end and an openend, means for directing a rod of high ymelting point material throughthe closed end of said combustion chamber along an axis toward the openend, means for directing llame -generally perpendicularly to the axisall around said rod, said combustion chamber including a preheating zonebetween said closed end and said -ame directing means, said Zone havinga length at least equal lto the radius of said chamber, means includingan outlet near ythe open end of the chamber Ifor providing a forcefulperipheral gas jet directed toward said rod and outwardly from thecombustion chamber, and means for bleeding gas under pressure into saidpreheating zone of said combustion chamber.

4. In combination, a combustion chamber having a closed end and an openend, means .for directing a rod of high melting point material throughthe closed end of said combustion chamber along an axis toward the openend, means for directing ilametoward and generally perpendicularly btothe axis, means for bleeding air under pressure into said combustionVchamber between said closed end and said llame directingmeans, andmeans including a peripheral outlet near the open-end of the chamber forproviding a forceful gas jet directed toward said -axis and outwardlyfrom the combusti-on chamber.

5. In combination, a combustion chamber having a first open end and asecond end having an aperture, said open end being constricted withrespect to the cross section of said combustion chamber to Vprovide anozzle, said nozzle beingan extension of Ithe combustion chamber, meansfor directing a rod of fused quartz through said -aperture along an axistoward the open end of said combustion chamber, `means for directingflame generally perpendicularly to sa-id axis to heat said rod to itsmelting point, and means including a peripheral outlet near the open endof Kthe chamber for providing a forceful gas jet .Y

directed toward said -axis and outwardly from the combustion chamberthrough the nozzle.

6. In combination, a combustion chamber having 'a closed end and 'anopen end, said open end being constricted with respect to the crosssection of said combustion chamber to provide a nozzle, said nozzlebeing an extension of the combustion chamber, means for directing a rodof high melting point material through the closed end of said combustionchamber along an axis toward the open end, means for directing flamegenerally perpendicularly to the axis, and outlet means near the openend of the chamber for providing a forceful peripheral gas jet directedtoward said axis and outwardly from the combustion chamber through thenozzle.

`7. In combination, a combustion chamber having a closed end and an openend, said open end being constricted with respect to the cross sectionof said combustion chamber to provide a nozzle, said nozzle being lanextension of the combusti-on cham-ber, means for directing a rod of highmelting point material through the closed end of said combustion chamberalong an axis toward the open end, means yfor directing llame generallyperpendicullarly to the axis all around said rod, said combustionchamber including a preheating zone between said closed end `and saidllame directing means, said zone having a length which is at least equalto the radius of said chamber, and outlet means near the open end of thechamber for providing a forceful peripheral gas jet directed toward saidaxis and outwardly from the combustion chamber through the nozzle.

8. In combination, a combustion chamber having a closed end and -an openend, said open end being constricted with respect to the cross sectionof said combustion chamber to provide a nozzle, said nozzle being anextension of the combustion chamber, means for directing la rod of highmelting point material through the closed end of said combustioncharnbel along an axis toward the open end, means for directing flametoward yand generally perpendicularly, to the axis, and means includinga continuous peripheral outlet near the open end of the chamber forproviding a forceful gas jet directed toward said axis and outwardlyfrom the combustion chamber through the nozzle.

9. In combination, a combustion chamber having a closed end and an openend, said open end being constricted with respect to the cross sectionof said combustion chamber to provide a nozzle, said nozzle being anextension of the combustion chamber, means for directing a rod of highmel-ting point material through the closed end of said combustionchamber along an axis toward the open end, means for directing jets ofpremixed fuel gas and oxygen toward and generally perpendicularly to theaxis, and means including an outlet near the open end of the chamber forproviding a forceful peripheral gas jet 7 directed toward said 'axis andoutwardly from the combustion chamber through the nozzle.

10. In combination, a combustion chamber having a closed end and lanopen end, said open end being constricted with respect to the crosssection of said combustion chamber to provide a nozzle, said nozzlebeing an extension of the combustion chamber, means for directing a rodof high melting point material through the closed end of said combustionchamber along an axis toward the open end, means for directing llametoward and generally perpendicularly to said axis, said llame directingmeans including separate jets for fuel gas and oxygen having outletslocated at common points around said rod, and means including an outletnear the open end of the chamber for providing a forceful peripheral gasjet directed toward said axis outwardly from the combustion chamberthrough the nozzle.

11. A combination as defined in claim 10 wherein said fuel gas andoxygen jets are concentric.

References Cited in the le of this patent UNITED STATES PATENTS

